LED series-resistor calculator — pick a resistor to light an LED safely

Pick a resistor that drops the leftover voltage at the LED's current. Drag the three inputs.

Supply voltage9.0 V

LED forward voltage2.0 V

LED current20 mA

Exact resistor

350Ω

to drop 7.0 V at 20 mA

Nearest E24 value

360Ω

gives 19.4 mA · 0.13 W